My all time favourite
Working on a local government desktop support temp contract as 'maternity cover'. One sunny August morning in the early 00's I got called to a remote office to swap out a 'faulty' desktop unit only to find it surrounded by about twenty assorted quartz crystals stuck into bits of play-dough in a complete 'magical' circle. User was nowhere in sight. Told she was on sick leave.
Unstuck the crystals and put them in a scrounged box and left them on top of a filing cabinet. Cleaned the desk of play-dough residue and replaced the unit with an identical loan Dell Desktop unit after cleaning dried on spill of local government instant coffee residue from underneath the desktop unit.
Checked replacement unit. Logged on using test account, no problem. Got another user in the office to log on via the machine. Checked remote connections to Netware servers for duplicates, Pinged the Internet proxy server and the email server. All working fine.
For the sake of a quiet life, took 'faulty' desktop unit back to base and decided to test it thoroughly. Everything worked properly, connected to the Internet and mail server using test account. An hour of testing and checking went by. Everything was working properly. Applications configured correctly, a number of duplicate profiles from repeated crashes in the file system, but nothing I couldn't fix in five minutes. Put desktop unit aside for ghosting new build.
Routine check on my support job queue the next morning showed a familiar office location flagging up. Support Manager is smirking at me. Same user. Oh Gawd. Phoned remote office to say unit had been replaced and all was working well when I left it. Same user was worrying about where all her crystals had gone "Because my computer is evil." Reassured her that I had replaced her computer completely and had sent it to be 'cleansed', then told her where her collection of 'protective crystals' were. Which seemed to mollify her.
The following week I swapped her old 'refreshed' unit back in. Didn't hear another peep after that because (According to Support Manager) said user had gone on extended sick leave. She was still on sick leave when my contract ended five weeks later and I moved on to another (and better) contract.